Any more knowledge? Probably not. It could be a wart or a cyst. I hope not a burrowed-in parasite. Whichever way, it could become a focal point for scratching, so I would take mousie to the vet to have it checked out and removed under proper sterile conditions. Even if it's only a sebaceous cyst, the vet folks should examine the contents, once they're removed, to make sure there is nothing else going on.

_________________ Zephyr Coco Bobby Noche Paiva April I loved you so / I still do / I always will / 'Twas Heaven here with you.